Focused Funds

No one's going to accuse the Pioneer Cullen Value fund of being a closet index fund. In a universe of thousands of stocks to choose from, the fund owns shares of just 41 companies.

Pioneer Cullen Value is what's called a "focused" fund. Such funds purchase fewer than 50 stocks; the typical domestic-stock fund holds two to three times that number. With most of its assets wedged into its top 10 holdings, a focused fund can't...